1. Field of the Invention
This invention relates to the prevention of needle contamination with skin air- or skin-borne microorganisms before a filled syringe with an attached hollow-bore needle stick is used to give a fluid injection and the prevention of accidental needle stick injuries capable of transmitting blood-borne infections to health care workers, clean up personnel and bye-standers after use of syringe-attached needle for withdrawing a body fluid from or giving a fluid injection into a subject.
2. Prior Art
The use of disposable conical puncture-resistant needle-sheaths or scabbards for shielding sharp hollow-bore steel needles attachable to the leading ends of syringes has been standard practice for many years. The trailing ends of the sheaths or scabbards customarily attach to the leading end of a hub on a hollow-bore needle by means of a reversible conical slip-connection; while the trailing end of the needle hub attaches to the leading end of the syringe by means of a reversible Luer-slip or a Luer-Lok connection. Because accidental needle sticks after use of the hollow-bore needle attached to the syringe are common, it is now generally recommended that the syringe user not attempt to resheath the needle with its originally supplied scabbard, or to use a one-handed procedure wherein the needle is resheathed by reinsertion into the scabbard. The instant invention resembles a standard needle scabbard, but differs in that hollow conical shield is structured to wedge impact the leading end of an inserted cylindric syringe barrel in its mid-portion, instead of forming a slip connection in its trailing end with a leading cone on the needle hub.
The use of three-part puncture-resistant shields or shielding systems which cover the entire syringe or syringe with an attached needle, is also semi-standard procedure in accordance with U.S. patented disclosures by Roehr et al U.S. Pat. No. 3,008,570 (Nov. 14, 1961), Higgins U.S. Pat. No. 3,110,309 (Nov. 12, 1963); Hamilton U.S. Pat. No. 3,367,488 (Feb. 6, 1968), Thackston U.S. Pat. No. 3,820,652 (Jun. 28, 1974), Wickham U.S. Pat. No. 4,237,882 (Dec. 9, 1980) assigned to Sherwood Medical Industries, and Shields U.S. Pat. No. 5,176,657 (Jan. 5, 1993). The patent of Wickham is currently embodied in the Monoject.RTM. system wherein the syringe with or without an attached hollow needle is sold enclosed in a three part shielding system comprising a scabbard for the needle, a scabbard for the syringe and a trailing cap which seals the system. In this system, the needle hub slip connects inside the leading scabbard which, in turn, slip connects inside the leading end of the trailing scabbard to hold the syringe within, when the leading scabbard is tightly affixed to the leading end of the needle hub and the trailing end of the needle hub is slip-fit or locked onto the leading syringe end of the syringe. If the leading needle scabbard is removed or is not tightly slip-connected to the trailing scabbard, the inserted needle and needle-connected syringe will fall out with inversion of the trailing scabbard. This maneuver indicates that there is no frictional impaction between the leading end of the syringe and the leading end of the trailing scabbard, even though this scabbard shielding the syringe is made in the form of a cone whose leading end slopes sharply inward to stop the leading end of the syringe and tightly hold the conical part of a needle hub.
Shields ('657) disclosed a three part shielding system wherein the trailing scabbard is coned such that it wedge impacts the leading end of a reusable cylindric dental cartridge aspirating syringe, such that an inserted cartridge with an attached hollow needle, after use, can be ejected safely through the breech of the syringe by displacement of the leading scabbard in a trailing direction. The three part shielding system was claimed as useful for sterile containment of the cartridge before use, for safe holding the syringe/needle between uses, and safely ejecting the spent cartridge with attached needle after use. However, the system was not claimed as applicable to disposable syringes with attachable needles. The instant invention resembles said trailing scabbard, but differs in that the leading end is closed, instead of open to slip fit with the leading scabbard.
The use of a cylindric protective case which slides over a cylindric cartridge aspirating syringe to keep the contents of the cartridge sterile was described by Rimbaud in U.S. Pat. No. 3,878,846 (Apr. 22, 1975). In the French Patent #2654-629A (02.11.89), Floquet disclosed a single use syringe comprising a barrel and needle protected by a stepped cylindric outer casing into which the syringe barrel and needle are withdrawn and locked in once the syringe has been used. Currently, as described in Advances in Exposure Prevention 1994; 1: 1-12 with supplementary drawings, Sherwood Medical Corporation produces and sells a safety syringe, Monoject.TM., having a cylindric guard which slides forward over the barrel of a syringe and locks with twisting to protect the leading tip of the syringe-attached needle after use. Similarly, Becton-Dickinson Corporation produces and sells a safety syringe, B-D Safety-Lok.TM., having a protective cylindric sliding sleeve which can be pushed forward and locked in place to protect the leading tip of the needle after use. Because none of these sliding cylindric needle shielding mechanisms are claimed as cones which simply wedge impact the leading end of an inserted cylindric syringe, none are applicable to the instant invention.
The instant invention also differs from patents pending for other kinds of conical shields for needles or syringes, in that the leading end of cone is closed.